COMPUTER SCIENCE
Binary
Put these into Size Order – 30secs
Data Storage Capacities
bit (a single 0 or 1 is a binary digit)
 8 bits = 1 byte
 1024 bytes = 1Kb
 1024 Kilobytes = 1Mb
 1024 Megabytes = 1Gb
 1024 Gigabytes = 1Tb

Learning Objectives


To understand that computers use the binary alphabet to represent all data and
instructions.
Understand the terms bit, nibble, byte, kilobyte, megabyte, gigabyte and terabyte
Success Criteria



ALL— will be able to state what binary is.
MOST— will be able to explain how computers use
binary and do simple binary conversions.
SOME— will create a spreadsheet that
automatically works out denary number from a
given binary number.
Rank these types of data storage in
size
RAM
Hard Drive
How Computers Work – Binary!




Computers are made up of complicated hardware that
stores and processes data.
If you break a computer down into its most basic components
you have millions of circuits that either allow electricity to
flow, or not.
Imagine a whole row of light switches that you can switch on
and off in different combinations to mean different things.
Each switch is either on or off. It only has two states. That is
why everything stored in a computer can be stored as a
series of 1s and 0s. This is called binary.
CPU / Processor/ Chip


The CPU is the brain of the computer – it tells the
computer what to do and when.
Has millions of tiny switches that can either be:
on or off
1 or 0
Denary System
0 , 1, 2, 3, 4, 5, 6, 7, 8, 9



We use a number system that uses 10 different
numbers. (Base 10 number system)
This is called the Denary System.
However computers don’t understand this as they only
understand 0’s and 1’s.
on or off
Denary System
243
3 units
Denary System
243
4 tens
4 * 10 = 40
Denary System
243
2 hundreds
2 * 100= 200
Denary System
2 hundreds
4 tens
3 units
2 * 100= 2004 * 10 = 40
243
Binary

Computers understand binary which is a Base 2 number
system as it only has two numbers:
0 and 1
Binary


The position of numbers in binary is also important.
Calculating denary number 1:
Denary
128
64
32
16
8
4
2
1
Binary
0
0
0
0
0
0
0
1
(1 * 1) = 1
Binary


The position of numbers in binary is also important.
Calculating denary number 3:
Denary
128
64
32
16
8
4
2
1
Binary
0
0
0
0
0
0
1
1
(1 * 2) = 2
(1 * 1) = 1
Binary


The position of numbers in binary is also important.
Calculating denary number 6:
Denary
128
64
32
16
8
4
2
1
Binary
0
0
0
0
0
1
1
0
(1 * 4) = 4
(1 * 2) = 2
Binary


The position of numbers in binary is also important.
Calculating denary number 37:
Denary
128
64
32
16
8
4
2
1
Binary
0
0
1
0
0
1
0
1
(1 * 32) = 32
(1 * 4) = 4
(1 * 1) = 1
Binary

Can you work out how to write the denary number 115
in binary?
Denary
128
64
32
16
8
4
2
1
Binary
0
1
1
1
0
0
1
1
64
32 16
2
1
Binary

Can you work out how to write the denary number 255
in binary?
Denary
128
64
32
16
8
4
2
1
Binary
1
1
1
1
1
1
1
1
128 64
32 16
8
4
2
1
Tip – Always use 8 bits for binary!
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So far we have only looked at numbers using eight
columns. This is an 8-bit number, or a byte.
00000011 is binary for 3 but so is 11.
You do not need the leading zeros for it to be a
valid number but we tend to write groups of 8 bits
because computers usually store data in bytes.
Binary Task

Work out the following numbers in binary:
Number
165
117
61
224
39
139
170
186
255
223
84
Binary
Binary Task - Answers

Work out the following numbers in binary:
Number
Binary
165
10100101
117
01110101
61
00111101
224
11100000
39
00100111
139
10001011
170
10101010
186
10111010
255
11111111
223
11011111
84
01010100
Extension
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
Can you create a spreadsheet that will
automatically work out the denary number from the
binary you type in (or vice versa?)
Validate it so you can only enter a 0 or 1
Review

What is binary? Explain this as if you are
explaining this to someone who knows nothing about
it.
HW

Complete the “Binary” questions on the VLE (it’s
Learning).